How does Joseph Conrad use imagery in The Secret Agent?

Conrad's vivid description of Michaelis' features illustrates the character's inability to connect to the outside world.

"His ideas were not in the nature of convictions. They were inaccessible to reasoning. They formed in all their contradictions and obscurities an invincible and humanitarian creed, which he confessed rather than preached, with an obstinate gentleness, a smile of pacific assurance on his lips, and his candid blue eyes cast down because the sight of faces troubled his inspiration developed in solitude"